JP5072222B2 - Developing roll production method and developing roll obtained thereby - Google Patents

Description

  The present invention relates to a method for producing a developing roll used in an electrophotographic copying machine, a printer, and the like, and a developing roll obtained thereby.

  A developing roll of an electrophotographic copying machine or the like is required to have toner chargeability and toner transportability. And in order to express these performances, it is important to uniformly roughen the roll surface. As such a developing roll, for example, as shown in FIG. 3, a rubber elastic layer 2 is integrally formed on the outer peripheral surface of the shaft body 1 by die molding, and further, a rough surface is formed on the outer peripheral surface. Examples include a developing roll on which a surface layer 4 formed by coating a coating liquid in which particles 3 are dispersed (see, for example, Patent Document 1).

Further, as shown in FIG. 4, an intermediate layer 5 is formed on the outer peripheral surface of the rubber elastic layer 2 by applying a coating liquid in which the rough surface forming particles 3 are dispersed, and the outer peripheral surface is further provided with a rough surface. A developing roll having a surface layer 6 formed by applying a coating liquid not containing the forming particles 3 has also been proposed (see, for example, Patent Document 2).
JP 2002-304053 A JP 2002-357949 A

  However, as in the above-mentioned Patent Document 1, in the case where the rough surface is formed by the rough surface forming particles 3 contained in the surface layer 4, the concave portion is relatively deep in the uneven shape appearing on the surface of the surface layer 4. Since the toner is easily formed, toner filming in which a toner external additive accumulates in the deepened portion occurs, and there is a risk of causing image defects due to occurrence of image unevenness and deterioration of fog characteristics. Further, when the coating liquid is applied to form the surface layer 4, the rough surface-forming particles 3 are likely to be non-uniform due to sedimentation or the like, so that the surface roughness of the surface layer 4 obtained varies from place to place. There is a problem that a stable roughness cannot be obtained.

  On the other hand, the thing of the said patent document 2 is coat | covered with the surface layer 6 which does not contain the rough surface formation particle | grains 3 in the outer periphery of the intermediate | middle layer 5 which dispersedly contained the rough surface formation particle | grains 3, and compared uneven | corrugated shape. Since it becomes gentle, toner filming hardly occurs, and image defects are considerably improved. However, when the intermediate layer 5 is formed, as in the above example, when the coating liquid is applied, the rough surface forming particles 3 are likely to be non-uniform due to sedimentation or the like. However, the problem that stable roughness cannot be obtained on the surface of the surface layer 6 has not been solved.

  SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides an excellent developing roll manufacturing method that has a stable surface roughness and does not cause image defects over a long period of time, and a developing roll obtained thereby. Is the purpose.

In order to achieve the above object, the present invention provides a rubber elastic layer formed directly or via another layer on the outer peripheral surface of a shaft body, and a coat layer formed on the outer periphery of the rubber elastic layer. And a step of preparing a rubber elastic layer forming material in which 5 to 25 parts by weight of rough surface forming particles having an average particle diameter of 5 to 20 μm are contained with respect to 100 parts by weight of a rubber component. By extruding the rubber elastic layer forming material on the outer peripheral surface of the shaft body or the outer peripheral surface of another layer formed on the outer periphery of the shaft body, unevenness due to the rough surface forming particles is formed. Steps for obtaining a rubber elastic layer formed on the surface, and coating the coating liquid not containing rough surface forming particles on the outer peripheral surface of the rubber elastic layer, thereby causing irregularities due to the irregularities on the surface of the rubber elastic layer. Obtaining a coat layer formed on the surface; The first gist is a method for producing a developing roll having

  In addition, the present invention is a coating layer formed on the outer peripheral surface of the rubber elastic layer, in which the surface roughness (Ra) is set to 0.5 to 2.5 μm. A method for producing a developing roll having a surface roughness (Ra) of 0.4 to 2.0 μm is set as a second gist.

  And this invention makes the developing roll obtained by the manufacturing method of the developing roll which is the said 1st or 2nd summary as a 3rd summary.

  That is, the present inventors have made a series of studies on a method for obtaining a uniform surface roughness on the surface of the developing roll in order to solve the above problems. As a result, when a coating liquid containing rough surface forming particles is applied to form a surface layer or an intermediate layer having uneven rough surfaces, unevenness of unevenness is avoided to some extent due to sedimentation of the rough surface forming particles. It turned out not to be. Therefore, as a result of further research on a method for forming irregularities that is completely different from the method of coating the coating liquid containing the rough surface forming particles, the rubber elastic layer forming material containing the rough surface forming particles is converted into a shaft body. When the outer surface of the rubber elastic layer is extruded to form irregularities on the surface of the rubber elastic layer, and the surface is further coated with a coating layer that does not contain the rough surface forming particles, the irregularities due to the irregularities on the surface of the rubber elastic layer are formed. It has been found that a developing roll formed on the surface of the coat layer and having a uniform rough surface on the whole can be obtained, and the present invention has been achieved.

  According to the method for producing a developing roll of the present invention, the entire surface of a rough surface that is uniform and has not been easy to obtain by simply replacing the rubber elastic layer forming step that has been conventionally performed by molding with extrusion molding. It is possible to easily obtain a developing roll having a high practical effect.

  And among the manufacturing method of the image development roll of this invention, it prepares especially so that the surface roughness (Ra) of the rubber elastic layer formed by extrusion molding may be 0.5-2.5 micrometers, and it forms in the outer peripheral surface When the surface roughness (Ra) of the coated layer is adjusted to 0.4 to 2.0 μm, a developing roll having more excellent characteristics can be obtained.

  Further, since the developing roller obtained by the production method of the present invention has a uniform uneven rough surface as a whole, it has excellent toner conveyance performance and does not cause uneven toner charging even after long-term use. . Therefore, a good image can be obtained over a long period of time. Further, since the rough surface forming particles are completely covered with the coating layer and are not exposed on the surface, there is no restriction on the chargeability and wear resistance, and the range of particle selection can be expanded.

  Next, embodiments of the present invention will be described in detail. The present invention is not limited to this embodiment.

  An embodiment of the developing roll of the present invention is shown in FIG. The developing roll includes a shaft body 10, a rubber elastic layer 11 formed along the outer peripheral surface of the shaft body 10, and a coat layer 12 formed on the outer periphery of the rubber elastic layer 11.

  As shown in FIG. 2 which is a schematic enlarged cross-sectional view of the rubber elastic layer 11, the rough surface forming particles 13 are dispersed and contained, and irregularities caused by the rough surface forming particles 13. Is formed on the surface of the rubber elastic layer 11. Further, irregularities due to the irregularities on the surface of the rubber elastic layer 11 are formed on the surface of the coat layer 12.

  The shaft body 10 is not particularly limited. For example, a metal hollow body or solid body is used. Examples of the material include stainless steel and aluminum. Further, an adhesive, a primer, etc. may be applied to the outer peripheral surface of the shaft body 10 as necessary in order to enhance the adhesiveness of the rubber elastic layer. May be made conductive.

  As a material for forming a rubber elastic portion (portion excluding the rough surface forming particles 13) of the rubber elastic layer 11 formed on the outer peripheral surface of the shaft body 10, for example, ethylene-propylene-diene rubber (EPDM), styrene- It is formed of butadiene rubber (SBR), silicone rubber, polyurethane elastomer or the like. Among these, it is preferable to use conductive silicone rubber from the viewpoint of low hardness and less sag. And various additives, such as a electrically conductive agent and silicone oil, can be suitably mix | blended with these rubber materials.

Examples of the conductive agent include carbon black, graphite, potassium titanate, iron oxide, c-TiO ₂ , c-ZnO, and c-SnO ₂ (where “c-” means conductivity). Things can be raised. Examples of the silicone oil include various types such as dimethyl silicone oil.

  The rough surface forming particles 13 used together with the rubber elastic portion forming material are not particularly limited, and examples thereof include silica, urethane resin, polyamide resin, fluororesin, acrylic resin, urea resin and the like. It is done. These may be used alone or in combination of two or more. When the rough surface forming particles 13 are elastic particles having a certain elasticity, the stress applied to the toner by the rough surface forming particles 13 is small, so that the toner may be crushed and chargeability may be impaired. Is small and suitable.

Moreover, the average particle diameter of the rough surface forming particles 3 is usually set in a range of 5 to 20 μm, and particularly preferably 5 to 15 μm. That is, if the average particle size is out of the range of 5 to 20 μm, it is difficult to provide the toner chargeability and toner transportability required for the developing roll. The average particle diameter of the rough surface forming particles 3 is a value derived using a sample arbitrarily extracted from the population. In addition, if the particle size is not uniform, as in the case of a particle shape that is not a true sphere but an elliptical sphere (a sphere with an elliptical cross section), the simple average value of the longest diameter and the shortest diameter is the particle diameter of the particle. To do.

The dispersion ratio of the rough surface forming particles 3 is based on 100 parts by weight (hereinafter abbreviated as “part”) of the rubber elastic layer 11 of the rubber elastic portion forming material (material excluding the rough surface forming particles 13). Must be set in the range of 5 to 25 parts. Especially, it is suitable to set to 5-15 parts. That is, even if the dispersion amount of the rough surface forming particles 3 is too large or too small, a uniform and optimum rough surface cannot be obtained on the roll surface.

  On the other hand, the material for forming the coat layer 12 is not particularly limited, and examples thereof include urethane resin, polyamide resin, acrylic resin, acrylic silicone resin, butyral resin (PVB), and the like. Used in combination with more than seeds. Of these, urethane resins are preferably used in terms of wear resistance. In addition to the above components, a conductive agent, a charge control agent and the like may be appropriately added as necessary.

  The material for forming the coating layer 12 is dissolved in an organic solvent and used as a coating solution. Examples of the organic solvent include methyl ethyl ketone (MEK), methanol, toluene, isopropyl alcohol, methyl cellosolve, dimethylformamide and the like. These may be used alone or in combination of two or more. In particular, it is preferable to use methyl ethyl ketone from the viewpoint of solubility in the forming material. Such a coating liquid preferably has a viscosity of 0.02 to 0.10 Pa · s from the viewpoints of coating properties, the influence on the roughness variation on the roll surface, and the like.

  The developing roll of the present invention can be produced, for example, as follows.

  That is, first, as the material for forming the rubber elastic layer 11, the material for forming the rubber elastic portion and the rough surface forming particles 13 are kneaded with a kneader such as a kneader to form the rubber elastic layer 11. Is made. Next, the rubber elastic layer 11 forming material is extruded onto the outer peripheral surface of the shaft body 10 and heated to vulcanize (condition: 130 to 200 ° C. × 5 to 60 minutes) to cure the extruded layer. Thus, the rubber elastic layer 11 is formed.

  On the other hand, a material for forming the coat layer 12 is dissolved in an organic solvent to prepare a coating liquid for forming the coat layer 12.

  Then, the coating liquid for forming the coat layer 12 is applied to the outer peripheral surface of the rubber elastic layer 11. The coating method is not particularly limited, and conventional methods such as a dipping method, a spray method, and a roll coating method can be applied. Then, after the coating, drying and heat treatment (vulcanization treatment, conditions: 120 to 200 ° C. × 20 to 90 minutes) are performed to remove the solvent in the solution of the coated coating solution. Layer 12 is formed. In this manner, a developing roll having a three-layer structure as shown in FIG. 1 can be produced.

  In the developing roll, the thickness of the rubber elastic layer 11 is preferably set in the range of 1 to 10 mm, particularly preferably 2 to 6 mm. Moreover, it is preferable to set the thickness of the coat layer 12 in the range of 3-30 micrometers, Most preferably, it is 8-25 micrometers. The thickness of the rubber elastic layer 11 and the thickness of the coat layer 12 can be obtained by taking a cross-sectional sample perpendicular to the axial direction of the developing roll and measuring it based on the micrograph.

  In the developing roll, the surface roughness (Ra) of the rubber elastic layer 11 extruded on the outer peripheral surface of the shaft body 10 is preferably set to 0.5 to 2.5 μm, more preferably. 0.8 to 2.0 μm. The surface roughness (Ra) of the coat layer 12 formed on the outer peripheral surface of the rubber elastic layer 11 is preferably in the range of 0.4 to 2.0 μm, more preferably It is in the range of 5 to 1.4 μm.

  That is, when the surface roughness (Ra) of the coat layer 12 is less than 0.4 μm, the surface of the coat layer 12 is too smooth, so that the supply of toner may be insufficient and the image density may be reduced. If the thickness exceeds 2.0 μm, the surface of the coat layer 12 is too rough and the image quality of the copied image may be uneven.

In addition, the said surface roughness (Ra) is calculated | required according to JISB0601: 1994, 9 points | pieces measured on the following measurement conditions using a contact-type surface roughness meter (Surfcom 480A, Tokyo Seimitsu Co., Ltd.). It is a value obtained by averaging measured values.
〔Measurement condition〕
Stylus diameter: 2 μm
Pressing pressure: 0.7mN
Measurement speed: 0.3 mm / sec
Measurement magnification: 5000 times Cut-off wavelength: 0.8 mm
Measurement length: 2.5mm
Measurement points: 9 points in the axial direction x 3 points in the circumferential direction

  The developing roll of the present invention is not limited to the three-layer structure shown in FIG. For example, an appropriate number of intermediate layers may be formed between the shaft body 10 and the rubber elastic layer 11 in accordance with the use of the roll, required characteristics, and the like to form a layer structure of four or more layers.

  Next, examples will be described together with comparative examples.

[Example 1]
First, an aluminum cored bar (outer diameter 6 mm) was prepared as a shaft serving as a cored bar, and an adhesive was applied to the outer peripheral surface of the cored bar. On the other hand, after kneading a material for forming a rubber elastic layer having the following composition with a kneader, a crosshead extruder (EM Engineering Co., Ltd., die diameter: 12.55 mm) is used on the outer peripheral surface of the core metal. Extruded into a cylindrical shape and vulcanized by heat treatment (170 ° C. × 30 min) to obtain a rubber elastic layer integrated with the cored bar.

[Composition of material for forming rubber elastic layer]
Silicone rubber (TCM5406U, manufactured by GE Toshiba Silicone) 100 parts Elastic particles (cross-linked urethane beads, C-800 transparent, manufactured by Negami Kogyo Co., Ltd .: average particle size 6 μm)
5 〃
Cross-linking agent (hydrosilyl cross-linking agent, TC-23B, manufactured by GE Toshiba Silicone) 1.2） Catalyst (platinum catalyst TC-23A, manufactured by GE Toshiba Silicone) 0.5〃

  Next, after preparing a material for forming a coating layer having the following composition, the coating layer is applied to the outer peripheral surface of the rubber elastic layer by a roll coating method and dried (180 ° C. × 30 min). To form a three-layer developing roll (see FIG. 1). In addition, the thickness of the rubber elastic layer of this developing roll is 3 mm, and the thickness of the coat layer is 15 μm.

[Composition of coating layer forming material]
PCD urethane resin (N5230, manufactured by Nippon Polyurethane Industry Co., Ltd.) 100 parts Carbon black (Dia Black # 3030, manufactured by Mitsubishi Chemical Corporation) 30 〃
MDI (Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) 30 〃

[Example 2]
In the rubber elastic layer forming material, 5 parts of non-elastic particles (cross-linked acrylic powder MX-500, manufactured by Soken Chemical Co., Ltd .: average particle size of 5 μm) were used as the rough surface forming particles instead of the elastic particles. Otherwise, a developing roll was produced in the same manner as in Example 1 above.

[Examples 3 to 6 , Reference Examples 1 and 2, Comparative Examples 1 to 4]
As shown in Tables 1 to 3 below, the configuration of the developing roll was changed. Other than that was carried out similarly to the said Example 1, and obtained the image development roll.

[Comparative Example 5]
A developing roll having the structure shown in FIG. 4 was produced as follows. That is, first, an aluminum cored bar was prepared as a shaft, and an adhesive was applied to the outer peripheral surface of the cored bar. Next, the core metal is set in the hollow part of the cylindrical mold, and a silicone rubber compound is poured into the gap between the cylindrical mold and the core metal, and then the mold is covered and heated. (180 ° C. × 5 minutes), the silicone rubber compound was vulcanized, and then demolded to produce a core metal with a rubber elastic layer. Next, urethane having an average particle diameter of 20 μm is added to a polymer solution obtained by mixing 100 parts of polyurethane elastomer (UN278, manufactured by Sakai Chemical Co., Ltd.), 20 parts of carbon black, 10 parts of a crosslinking agent, and 400 parts of MEK. A solution for forming an intermediate layer was prepared by dispersing, mixing, and stirring 20 parts of particles for forming a rough surface made of resin (Bernock CFB100, manufactured by Dainippon Ink & Chemicals, Inc.). Further, a surface layer forming solution was prepared by mixing 100 parts of urethane resin (Nipporan 5199, manufactured by Nippon Polyurethane Industry Co., Ltd.), 20 parts of carbon black, and 400 parts of MEK. And after applying the said intermediate | middle layer formation solution to the outer peripheral surface of the said rubber elastic layer by the roll coat method, it dried and heat-processed and formed the intermediate | middle layer. Furthermore, after the surface layer forming solution was applied to the outer peripheral surface of the intermediate layer by a roll coating method, drying and heat treatment were performed to form a surface layer. The thickness of the rubber elastic layer of this developing roll is 3 mm, the thickness of the intermediate layer is 10 μm, and the thickness of the surface layer is 15 μm.

For each of the developing rolls of Examples 1 to 6 , Reference Examples 1 and 2, and Comparative Examples 1 to 5, the surface roughness (Ra) and the image evaluation after durability were evaluated according to the following method, and the results are described later. We were shown together in Table 1 to Table 3.

[Surface roughness (Ra)]
For the developing rolls of Examples 1 to 6 , Reference Examples 1 and 2, and Comparative Examples 1 to 4, first, when the rubber elastic layer was formed, the surface roughness (Ra) of the surface was determined according to the method described above. It was. Further, when the coating layer was formed on the outer peripheral surface of the rubber elastic layer, the surface roughness (Ra) of the surface (developing roll surface) was determined in the same manner. For the developing roll of Comparative Example 5, only the surface roughness (Ra) of the surface layer was determined.

(Image evaluation)
The developing roll was incorporated into an electrophotographic printer and 10,000 sheets were actually printed. Then, the printed image is observed visually, there is no problem with the printed image, ○ is clearly printed up to the fine line, △ is slightly blurred or fogged, and the blurred or fogged is obvious. What occurred in was marked with x. The fading means that the thin line is broken, and the fog means that the toner is flying in a place where there is no image.

From the results of Tables 1 to 3, all of the Example products have good image evaluation after endurance, whereas the Reference Example product and Comparative Example product both have poor image evaluation after endurance. Recognize.

It is sectional drawing which shows one Example of the image development roll of this invention. It is a typical partial expanded sectional view of the said Example. It is a typical partial expanded sectional view of the conventional image development roll. It is a typical partial expanded sectional view of the other conventional developing roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shaft body 11 Rubber elastic layer 12 Coat layer 13 Rough surface forming particles

Claims (3)

A process for producing a developing roll comprising a rubber elastic layer formed directly or via another layer on the outer peripheral surface of a shaft body, and a coat layer formed on the outer periphery of the rubber elastic layer, the average particle diameter A step of preparing a rubber elastic layer forming material containing 5 to 25 parts by weight of a rough surface forming particle of 5 to 20 μm with respect to 100 parts by weight of a rubber component, and the outer peripheral surface of the shaft body or the outer periphery of the shaft body By extruding the rubber elastic layer forming material on the outer peripheral surface of the other layer formed to obtain a rubber elastic layer having irregularities due to the rough surface forming particles formed on the surface; Applying a coating liquid containing no rough surface forming particles to the outer peripheral surface of the rubber elastic layer to obtain a coating layer having irregularities due to the irregularities of the rubber elastic layer surface formed thereon. Production of a developing roll characterized by comprising Law.   The surface roughness (Ra) of the rubber elastic layer formed by extrusion is set to 0.5 to 2.5 μm, and the surface roughness (Ra) of the coat layer formed on the outer peripheral surface is set to 0.4 to The method for producing a developing roll according to claim 1, wherein the developing roll is set to 2.0 μm.   A developing roll obtained by the method according to claim 1 or 2.

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